Electric utilities need to have a power generating capacity sufficient to supply the peak load on the power generating system. The peak load varies both daily and seasonally and the cost of providing power has a direct relationship with the peak daily load as well as the peak seasonal load. To reduce costs, it is highly desirable, to the extent possible, to transfer power use on a daily basis from the periods of peak load to periods of off-peak load. One electrical appliance which is particularly suitable for shifting the time that it is energized is the electrical water heater. Conventional electrical water heaters are equipped with a thermostat which turn the heating element of the water heater on and off in accordance with the temperature of the water in the tank and accordingly, are turned on and off without any regard to the periods of peak load intervals for power use. On the other hand, the use of electrical power to energize the heating element and heat the water in the water heater can be delayed with little or no inconvenience to the consumer. The reason for this fact is that when hot water is used from a hot water tank, it is replaced by cold water in the bottom of the tank, but the cold water does not mix with the hot water. As a result, most of the hot water can be drawn from the tank without any noticeable drop in the temperature of the hot water being drawn off. Thus, a time shifting of the energization of the heating element to an off-peak time period will in most instances, not inconvenience the user who can still draw an amount of hot water during the peak period approaching the capacity of the water heater tank. This fact is particularly true when the water heater tank is of thermal storage type, which has a large capacity.